Hi All,
I was looking for a means of testing my headlight range adjuster motors so I had a look at the circuit diagram.
I devised a battery powered tester which could be plugged into the connector on or off the car.
This replicates the control on the dash.
It requires some simple electronics knowledge and involves some soldering.
The parts required are:
2 x 2 pin mains connector leads (used on old radio cassettes, VCRs, Sky boxes etc.)
1 x 1k ohm potentiometer (“pot”). These come in a variety of shapes and sizes, try to find one with an attached knob. Currently on eBay for under £2 posted, don’t buy the sub-minature ones with just a screwdriver slot.
390R (ohm) resistor
PP3 battery connector
PP3/MN1604 Alkaline battery
This is the type of mains cable:
First cut the cables down to about 40cm, then strip the outer sheaths from both cables.
The redundant plugs should have the fuses removed for safety before disposal.
Cut one of the plugs down the centre to make a single pin plug.
Use the blue wire, discard the brown.
Sorry, this one's blurred:
The single plug is now taped to the blue wire side of the double plug. Use a strip of Duct tape as it doesn’t stretch. Apply the tape about 10mm back from the pins so that it won't foul the socket on the motor. So now you’ve got a 3 pin plug, brown, blue, blue.
The circuit can now be made up.
More on the "pot", conventionally the centre solder connection is the "slider" It doesn't matter here which which way round that you attach the wires to the end connections as it does not have a polarity. The pot I used here does not follow the normal convention. The ones on eBay do.
The end blue wire (the single pin plug) is connected to one end of the pot, connection “G” on motor.
The centre blue is connected to the battery (-) and to the other end of the pot, connection “31” on motor.
The brown is connected to one end of the 390R resistor and the battery (+), connection “56b” on motor.
The other end of the 390R resistor is connected to the "slider" of the pot, the centre connection.
G, 31 and 56b are written close to each of the connecting pins on the motor body (or at least they were on my Hella ones!)
You will see that the socket on the motor has 3 “V” shaped notches arround it. The plug is inserted with the brown to the end with the 2 “V” notches that face each other.
By rotating the pot the motor should be heard to turn and the headlamps will slowly rise and fall.
If the motor is off the car, mark a line on the ball pin so the movement in and out can be seen. It is slow, even slower because of using a 9 volt battery not 12.
I realise that if you have to go to the trouble of sourcing the components this may not be as useful as it was to me. I have all sorts of c**p lying about so I'm seldom short of anything!
One point of caution, if you are tempted to unclip the case, don't just try to pull it off, you will bend a copper colour spring finger. Pull it appart gently just until you get a small gap between the case and top. slide a thin tool, a plastic card would do, in between the circuit board and the case top, gently prise these appart, pushing the circuit board back into the case. The top cover itself will then be unplugged from the circuit board. As far as I can tell the copper spring is the last part to be fitted in assembly and limits how much stripping of the motor you can do. Strip it at your own risk!
I was looking for a means of testing my headlight range adjuster motors so I had a look at the circuit diagram.
I devised a battery powered tester which could be plugged into the connector on or off the car.
This replicates the control on the dash.
It requires some simple electronics knowledge and involves some soldering.
The parts required are:
2 x 2 pin mains connector leads (used on old radio cassettes, VCRs, Sky boxes etc.)
1 x 1k ohm potentiometer (“pot”). These come in a variety of shapes and sizes, try to find one with an attached knob. Currently on eBay for under £2 posted, don’t buy the sub-minature ones with just a screwdriver slot.
390R (ohm) resistor
PP3 battery connector
PP3/MN1604 Alkaline battery
This is the type of mains cable:
First cut the cables down to about 40cm, then strip the outer sheaths from both cables.
The redundant plugs should have the fuses removed for safety before disposal.
Cut one of the plugs down the centre to make a single pin plug.
Use the blue wire, discard the brown.
Sorry, this one's blurred:
The single plug is now taped to the blue wire side of the double plug. Use a strip of Duct tape as it doesn’t stretch. Apply the tape about 10mm back from the pins so that it won't foul the socket on the motor. So now you’ve got a 3 pin plug, brown, blue, blue.
The circuit can now be made up.
More on the "pot", conventionally the centre solder connection is the "slider" It doesn't matter here which which way round that you attach the wires to the end connections as it does not have a polarity. The pot I used here does not follow the normal convention. The ones on eBay do.
The end blue wire (the single pin plug) is connected to one end of the pot, connection “G” on motor.
The centre blue is connected to the battery (-) and to the other end of the pot, connection “31” on motor.
The brown is connected to one end of the 390R resistor and the battery (+), connection “56b” on motor.
The other end of the 390R resistor is connected to the "slider" of the pot, the centre connection.
G, 31 and 56b are written close to each of the connecting pins on the motor body (or at least they were on my Hella ones!)
You will see that the socket on the motor has 3 “V” shaped notches arround it. The plug is inserted with the brown to the end with the 2 “V” notches that face each other.
By rotating the pot the motor should be heard to turn and the headlamps will slowly rise and fall.
If the motor is off the car, mark a line on the ball pin so the movement in and out can be seen. It is slow, even slower because of using a 9 volt battery not 12.
I realise that if you have to go to the trouble of sourcing the components this may not be as useful as it was to me. I have all sorts of c**p lying about so I'm seldom short of anything!
One point of caution, if you are tempted to unclip the case, don't just try to pull it off, you will bend a copper colour spring finger. Pull it appart gently just until you get a small gap between the case and top. slide a thin tool, a plastic card would do, in between the circuit board and the case top, gently prise these appart, pushing the circuit board back into the case. The top cover itself will then be unplugged from the circuit board. As far as I can tell the copper spring is the last part to be fitted in assembly and limits how much stripping of the motor you can do. Strip it at your own risk!
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